挤压Zn-Cu-Ti合金的组织及其力学性能

Microstructure and Mechanical Properties of Extruded Zn-Cu-Ti alloys

采用Zn-Ti中间合金等制备了不同铜含量的锌合金,370℃/4h均匀化后在300℃对合金进行了热挤压加工。通过X射线衍射分析、扫描电镜分析和能谱分析以及力学性能测试,研究了合金的微观组织和力学性能之间的关系。结果表明,Zn-Cu-Ti合金主要由锌的固溶体η相,TiZn15相和CuZn4相组成,Ti元素的加入细化了合金的显微组织,提高了合金的力学性能;热挤压过程中,合金发生动态再结晶和局部再结晶晶粒长大现象,TiZn15相和CuZn4相被破碎后沿挤压方向分布于晶界处,有助于阻碍再结晶晶粒的长大;Cu含量在0.5%~3.0%范围内,随着含铜量的增加,Zn-Cu-Ti合金的强度和硬度增大,当Cu含量超过2.0%时伸长率有下降趋势;由于挤压过程中发生了动态再结晶在一定程度上抵消了加工引起的硬化,合金挤压态硬度较铸态硬度提高不大。

Zn-2.0Cu alloy and a serials of extruded Zn-Cu-Ti alloys with 0.5wt% to 3.0wt% Cu and 0.2wt% Ti were prepared by melting the mixture of Zn-Ti,Zn-Cu intermediate alloys and high purity Zinc.After having been homogenized at 370℃ for 4h,the alloys were extruded at 300℃.Microstructure characteristics and mechanical properties were investigated by X-ray diffractometry（XRD）,scanning electron microscopy（SEM）,X-ray energy-dispersive spectroscopy（EDS）,and mechanical property tests.The results showed that,TiZn_15 and CuZn_4 intermetallics formed and the primary intermetallic phase TiZn_15 refined which helps to improve mechanical properties of the alloys.After having been extruded,dynamic recrystallization happened in the zinc-riched solid solution,and the TiZn_15 and CuZn_4 phases were scrapped and oriented along the extruding direction,which helps to suppress the growth of grains;Tensile strength and Vickers hardness increased with increasing copper content in the range of 0.5% to 3.0%,but the maximum elongation of 49% occurred when the content of Cu was 2%.Due to the dynamic recrystallization,the HVs of extruded alloys were not quite higher than the ascast alloys.